#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<stdlib.h>
int main() {
	char arr[10];
	int arr1[128] = { 0 };
	int max = 0;
	gets(arr);
	for (int i = 0; i < strlen(arr); i++)
	{
		arr1[(int)arr[i]] = 1;
	}
	for (int i = 0; i < sizeof(arr1) / sizeof(arr1[0]); i++)
	{
		if (arr1[i] == 1)
			max++;
	}
	printf("%d", max);
}